1. Field of the Invention
The present invention relates to an active vibration isolating support device comprising an elastic body for bearing the load of a vibratory body, a liquid chamber at least partially constituted by said elastic body, a movable member for changing the capacity of the liquid chamber and an actuator for driving an armature connected to the movable member by virtue of an electromagnetic force produced by a coil.
2. Description of the Related Art An active vibration isolating support device as described above is known in Japanese Patent Unexamined Publication No. Hei. 10-110771(JP-A-10-110771).
In this active vibration isolating support device, the movable member for changing the capacity of the liquid chamber is constituted by a disc-like plate spring secured to a case around the periphery thereof, and the armature driven by the coil of the actuator does not have any specific bearing and is supported directly on a lower surface of the movable member at a central portion thereof. The armature is then constructed so as to be attracted by exciting the coil, and the movable member integrally joined to the armature is reciprocated in directions along the axis of the device.
In this active vibration isolating support device, in addition, a driving signal is calculated based on a reference signal outputted every time a crank shaft rotates through a predetermined angle and a residual vibration signal transmitted from the engine to the frame of the vehicle body via the active vibration isolating support device, and the actuator is constructed so to be feedforward controlled.
In this conventional active vibration isolating support device, when the movable member for changing the capacity of the liquid chamber is deviated from the axis of the device by a biassed load the movable member receives from the liquid in the liquid chamber, since the armature is not supported by a bearing, the armature made integral with the movable member is also inclined. Thus, an air gap needs to be set so wide as to avoid a risk of the armature being brought into contact with a yoke even if it is inclined, this resulting in deterioration of the characteristics of the magnetic circuit. To solve this problem, the magnetic force to be generated may be increased by enlarging the coil, but such a construction leads to increase in power consumption of the coil.
To cope with this, it is then considered to avoid a contact between the inclined armature and the yoke by supporting the armature by a bearing such that the armature moves along the axis of the device, but such a construction generates pinching between the armature and the bearing due to a biassed load imparted by the movable member, and it leads to a problem that the bearing wears too early, whereby the durability of the actuator is reduced.
In addition, since the conventional active vibration isolating support device is provided with no means for verifying the operational amount of the armature, even if the actuator fails and becomes out of order or the actuator gets deteriorated and the operational amount thereof is reduced, there is no way of detecting such an abnormal state, and this may result in a problem that the active vibration isolating support device cannot perform as originally designed. Furthermore, since the operational amount of the actuator cannot be detected, the operation of the actuator cannot be feedback controlled, and this results in a problem that control with high accuracy is made difficult.
The present invention was made in view of the aforesaid situation and an object of the invention is to provide an active vibration isolating support device which can reduce the power consumption thereof without deteriorating the durability of the actuator for driving the movable member.
In addition, the other object of the invention is to provide an active vibration isolating support device which can ensure the detection of the abnormal state of the actuator.
With a view to attaining the objects, according to a first aspect of the invention, there is provided an active vibration isolating support device comprising an elastic body for bearing the load of a vibratory body, a liquid chamber at least partially constituted by the elastic body, a movable member adapted to change the capacity of the liquid chamber, and an actuator for driving an armature connected to the movable member by virtue of an electromagnetic force produced by a coil, the active vibration isolating support device has the armature which is supported by a bearing, wherein the armature and the movable member are connected to each other in a flexible fashion, and are accommodated to be bent.
According to the above construction, since the armature of the actuator is supported by the bearing, the vibration of the armature can be prevented, whereby an optimum air gap can be set for the actuator, thereby making it possible to miniaturize the coil to thereby reduce the power consumption. Moreover, since the armature and the movable member are connected to each other in a flexible fashion, even if there occurs a vibration of the movable member due to the load imparted by the liquid chamber, the vibration is not directly transmitted to the armature, whereby biassed wearing of the bearing can be prevented, thereby making it possible to improve the durability and reliability of the actuator.
In addition, according to a second aspect of the invention, there is provided an active vibration isolating support device comprising an elastic body for bearing the load of a vibratory body, a liquid chamber at least partially constituted by the elastic body, a movable member adapted to change the capacity of the liquid chamber, and an actuator for driving an armature connected to the movable member by virtue of an electromagnetic force produced by a coil, the active vibration isolating support device being characterized in that the armature supported by the bearing and the movable member are adapted to be brought into contact with each other at a contact portion in such a manner as to be displaced relative to each other and that the armature is adapted to press drive the movable member via the contact portion when the armature is attracted by the coil when the coil is excited.
According to the above construction, since the armature of the actuator is supported by the bearing, the vibration of the armature can be prevented, whereby the optimum air gap can be set for the actuator and consequently, the coil can be miniaturized to thereby reduce the power consumption. Moreover, since the armature and the movable member are brought into contact with each other via the contact portion such that they can be displaced relative to each other, even if the vibration of the movable member is generated by the load imparted thereto by the liquid chamber, the vibration is constructed so as not to directly be transmitted to the armature, whereby the biassed wear of the bearing can be prevented, thereby making it possible to improve the durability and reliability of the actuator. Furthermore, since the armature press drives the movable member via the contact portion, the deviation of the armature from the movable member can be prevented, whereby the movable member can securely be driven.
An engine E that will be described in first and second modes for carrying out the invention corresponds to the vibratory body described in the above first and second aspects of the invention, a first elastic body in the first and second modes for carrying out the invention corresponds to the elastic body discussed in the above first and second aspects, and a first liquid chamber in the first and second modes corresponds to the liquid chamber of the above aspects of the invention.
Furthermore, according to a third aspect of the invention, there is provided an active vibration isolating support device comprising an elastic body for bearing the load of a vibratory body, a liquid chamber at least partially constituted by the elastic body, a movable member adapted to change the capacity of the liquid chamber, and an actuator for driving an armature connected to the movable member by virtue of an electromagnetic force produced by a coil, the active vibration isolating support device has a operational amount detecting means for detecting an operational amount of the actuator.
According to the above construction, since the operational amount of the actuator of the active vibration isolating support device is detected by the operational amount detecting means, not only can an abnormal state be securely detected in which the actuator fails and becomes out of order or in which the actuator becomes deteriorated and the operational amount thereof is reduced but also a feedback control can be performed in which a detected operational amount is made to coincide with a target value.
An engine E that will be described in a third mode for carrying out the invention corresponds to the vibratory body described in the above third aspect of the invention, a first liquid chamber in the third mode corresponds to the liquid chamber of the above third aspect, and a lift amount sensor to be described in the third mode corresponds to the operational amount detecting means discussed in the above third aspect of the invention.